Current minimally invasive surgical procedures rely on endoscopes for visualization of the surgical site. In the arthroscopy, laparoscopy, urology, gynecology, and ENT (ear, nose, and throat) specialties, rigid endoscopes are primarily used. A rigid endoscope is constructed of an inner lumen containing multiple glass lens elements for visualization and an outer lumen containing a bundle of fiber optic strands for carrying light from a light source to the surgical site.
Conventional surgical light systems are very inefficient. From the light engine, which is typically a metal halide bulb, halogen bulb, xenon bulb, or LED(s) (light emitting diode), to the surgical site over ninety-five percent of the light is lost. These losses occur at multiple locations, the first being at the optic placed in front of the light engine to gather the light from a wide dispersion angle and focus it into a collimated beam with a diameter small enough to transmit to a fiber optic light cable. The second loss point is the junction of the focusing optic and the aforementioned fiber optic light cable. The fiber optic light cable is a bundle, typically with a diameter of five millimeters, of small fiber optic strands and measures one to three meters in length. The third loss point is over the length of the fiber bundle due to the attenuation rate of the bulk fiber strands. The fiber optic light cable transmits light from the light source to the endoscope in sterile field. The fourth loss point is the junction between the light cable and the proximal end of the endoscope.
Due to the losses in the light transmission path, the light source must generate a significant amount of light. This results in a significant amount of heat generated, particularly at each of the junction points and at the distal tip of the scope. The heat generated, specifically at the distal scope tip and at the junction between the light cable and scope, can present a safety risk to the surgical patient. The heat is such that if the scope is inadvertently rested on the patient for a period of time, a burn can occur. This is an issue with all conventional light sources and every year a few such incidents occur and are reported to the FDA (Food and Drug Administration).